Liquid crystal display (LCD) is a flat panel display device using the characteristics of the liquid crystal materials to display images which has many advantages, such as lightweight, low driving voltage and low power consumption, and has becoming the mainstream products in the whole consumer market.
Liquid crystal panel is the most important component of the LCD which contains a thin film transistor (TFT) array substrate and a color filter (CF) substrate that are laminated in vacuum, a liquid-crystal layer and alignment films filled between them. The alignment films are equipped on the TFT array substrate and/or CF substrate to control the predetermined initial arrangement of liquid crystal molecules of the liquid-crystal layer in order to influence the performance of the liquid crystal panel.
Polymer stabilized vertical alignment (PSVA) technology has becoming the mainstream because of the features of high penetration rate, high contrast and fast response. In the conventional PSVA technology, liquid crystal reactive monomer (RM) is doped in to liquid crystal, after applying voltage, a pretilt angle of the liquid crystal molecules is produced and the RM is linked to polyimide (PI) of alignment films, and lastly, after UV exposure, polymerizable monomers come into polymer and the pretilt angle of the liquid crystal molecules is fixed.
But, there are problems in conventional PSVA technology, such as limited choices of liquid crystal molecule, poor compatibility of liquid crystal molecule and RM, transportation and storage problems, etc.
Surface controlled vertical alignment (SCVA) technology is developed to solve the problems of PSVA technology. Compared with PSVA technology, in SCVA technology, RM is doped in alignment materials so that there are more choices of crystal molecule, and SCVA technology does not suffer compatibility issue of liquid crystal molecule and RM, transportation issue and storage issue; meanwhile, SCVA technology also has advantages including less impurities, high reliability, etc. However, the voltage (30V) applied on substrates in SCVA technology is higher than the voltage (10V) applied on substrates in PSVA technology, and the pretilt angle of liquid crystal molecules (less than 1°) is so small that the response time of the display is too long.
As a result, it is necessary to provide the improvement of the existing technology to solve the problems existing in the conventional technologies.